1. Field of the Invention
The invention relates to a media-conveying apparatus, and more particularly, to a media-conveying apparatus in a printer.
2. Description of the Prior Art
Printers are used to print information on a media (such as paper). Printers usually have a media-conveying apparatus to convey the media and make printers capable of printing on different areas of the media. Most media-conveying apparatuses use rollers to drive the media. But for some printers, such as inkjet printers, print by applying liquid dye to the media. To avoid staining the rollers with liquid dye while the media is being driven, the printing apparatus usually uses star-wheels, or called spurs. The star-wheel has a plurality of tips around an edge and uses the tips to contact to the printed media. Since the contact area between a tip and the printing media is quite small, printing quality is not reduced if attached dye is still wet. In addition, for the media-conveying apparatus to use printing media of different thicknesses, a printing apparatus of the prior art has an elastic apparatus for elastically pressing on the star-wheel so the star-wheel can move vertically according to the printing media thickness when the media-conveying apparatus is conveying printing media.
Please refer to FIGS. 1 and 2. FIG. 1 is a schematic diagram of a media-conveying apparatus 20 of the prior art used in a printing machine 10. FIG. 2 is a cross-sectional diagram of a media-conveying apparatus 20 of FIG. 1 along line 2xe2x80x942. The media-conveying apparatus 20 is used in printer 10 to convey a printing media 28. The media-conveying apparatus 20 has a support 46 for placement of other parts of media-conveying apparatus 20, a rotational arm 24 rotating around a fixed support point 36, a spring 26 with one end fixed on support 46 for elastically pressing a first arm 32 of rotational arm 24, a star-wheel 22 having a plurality of tips 38 around its circular edge and a roller 42 below star-wheel 22 to drive printing media 28. Rotational arm 24 further has a second arm 34. Star-wheel 22 is rotatable and is set on an axle that is placed on second arm 34.
When roller 42 is driving printing media 28, because the spring 26 elastically presses the first arm 32 of rotational arm 24, the printing media 28 is nipped between star-wheel 22 and roller 42, and tips 38 of star-wheel 22 elastically contact printing media 28. So star-wheel 22 can accommodate printing media 28 of different thicknesses due to spring 26.
Please refer to FIG. 3 of a cross-sectional diagram of a media-conveying apparatus 50 of another prior art. The media-conveying apparatus 50 has a support 68 for placing other parts of the media-conveying apparatus 50, a cylinder 62 having a support point 64, a star-wheel 54 having a plurality of tips 56 around an edge, a spring 52 with one end fixed on support 68 for elastically pressing on arm 62 and a roller 58 below star-wheel 54 for driving printing media 66. Star-wheel 54 uses support point 64 as a center and is set on arm 62. When roller 58 is driving printing media 66, spring 52 elastically presses the arm 62, printing media 66 is nipped between the star-wheel 54 and the roller 58 and the tips 56 of star-wheel 54 elastically contact to printing media 66.
Printing apparatuses 20 and 50 of prior arts have a weakness in that spring 26 and 52 are fixed on supports making maintenance and replacement of springs 26 and 52 difficult. In addition, media-conveying apparatuses 20 and 50 of prior arts have more components and are manufactured manually in a complex assembly process.
It is therefore a primary objective of the present invention to provide a media-conveying apparatus to solve the above-mentioned problem.
Briefly, in a preferred embodiment, the present invention provides a media-conveying apparatus comprising:
a support;
a star-wheel having a plurality of tips around an edge;
a wheel axle through a center of the star-wheel; and a monolithic first elastic apparatus having a first torsion arm placed on the support and a second torsion arm for pressing the axle to make the tips of the star-wheel elastically contact a printing media.
It is an advantage of the present invention that the media-conveying apparatus according to the present invention has fewer parts and is easy to assemble and maintain.
These and other objects and the advantages of the present invention will no doubt become obvious to those of ordinary skill in the art after having read the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.